[pointyst1k]

Okay, I typed this out a long time ago and fully understood it, now not so much. I have 30mL droppers and I need to measure out how much per drop I am going to expel. Here's what I wrote (Man, I wish I did a better job writing it). If someone could please write the equation out more understandable, and site and example it would be very much appreciated.

COMPOUNDmg(VOLUMEPERDROPmL/MASSWANTEDmg)=
                         MASSmg(ANSWERmL/mg)=



Thanks in advance!

[Borek]

Doesn't make much sense to me.

In general - you either need to know how many drops are there per 30 mL, then the amount per drop is simply

total amount in a dropper/number of drops in 30 mL

or you need to know the volume of a single drop - and then the amount per drop is

concentration of the solution in the dropper*drop volume

Amount of drops per mL depends on the drop dispenser, typically it is around 20 drops per mL. Can be less, can be more.

[Arkcon]

Furthermore, often drops per mL will depend on the force you exert, which will often depend on your mood, or how tired you are, and other factors.  You might want to test this out for yourself multiple times, if you're going to rely on this measurement.

[pointyst1k]

This has been figured out before. There .5mL per drop, it's a 30mL dropper, I want 12.5mg of the compound in it per drop. What I'm trying to figure out in algebraic form is how many mg's of this compound I will need to equal 12.5mL per drop in the 30mL container.

My original algebraic expression is close. And there are going to be variables with this, but please, just consider the numbers at absolute fact. Thanks..

[pointyst1k]

Okay, I went over some old notes in a notebook that I jot random stuff down, and I think I got lucky.

Drop Volume/Compound Dose=
        Compound Weight(Answer)=

I think this is correct. Right? I need a formula that gives me how much compound to use, as per mg per drop.

[mjc123]

I think this is correct. Right?

No, it's meaningless. You have two expressions, each with an equals sign and nothing on the right hand side.

I need a formula that gives me how much compound to use, as per mg per drop.

You have already said you want 12.5 mg per drop. Do you mean how many mgs in the full dropper to give you 12.5 mg per drop?
0.5 mL sounds like a very large drop. Are you sure it's not something like 0.05 mL - that would be more typical for a dropper.
Anyway, if you know the volume of the drop (call this v), and the total volume of the dropper (call this V), how many drops are there in a full dropper?
So if there are 12.5 mg in one drop, how many mg are there in a full dropper?